This study intends to evaluate: (1) the pharmacokinetics of intravenously administered ZVD and orally administered ZVD in third trimester HIV-1 pregnant women; (2) the safety of chronically administered oral ZVD in third trimester HIV-1 pregnant women; (3) the pharmacokinetics of ZVD and urinary excretion of ZVD and its metabolites in the newborn of HIV-1 infected mothers who received ZVD during their third trimester.